This invention relates to a fluid control system for operating actuators. More particularly, the invention is directed to a fluid control system for operating multiple actuators in independent and regenerative function modes.
Some fluid control systems operate a double-acting actuator with a regeneration capability. The fluid control systems with this regeneration capability direct some of the fluid exhausted from a contracting chamber of a double-acting actuator to an expanding chamber of the actuator.
In the past, a regeneration valve is disposed between a main directional control valve and an actuator to provide a quick drop capability to the actuator driven in one direction by gravity loads. In such a configuration, however, an operator has little or no control over the amount of regenerated fluid recirculated from the contracting chamber to the expanding chamber.
A fluid control system with a relatively simple regeneration capability has been provided in association with a pump, a tank, and a double-acting actuator having a pair of actuating chambers. For example, U.S. Pat. No. 6,161,467 discloses a fluid control system having a regeneration capability. The system includes a pump, a tank, two double-acting actuators having actuating chambers, and a control valve. The control valve moves from a first position to a second position in a regeneration mode. This fluid control system, however, does not allow operation of the multiple actuators both regeneratively and independently. It is desirable to provide a fluid control system that provides accurate control of the actuators and is compact in size.
Accordingly, the present invention is directed to overcoming one or more of the problems as set forth above.
In one aspect of the invention, a fluid control system includes a first double-acting actuator and a second double-acting actuator. A first independent metering valve has a first control port connected to the first double-acting actuator, a second control port connected to the second double-acting actuator, first and second independently operable valves disposed between the inlet port and the first and second control ports, and a first check control mechanism having a main check valve between the inlet port and the first and second independently operable valves. The first check control mechanism controls the main check valve to allow the first and second actuators to operate in either an independent function mode or a regenerative function mode. A second independent metering valve has a first control port connected to the first double-acting actuator, a second control port connected to the second double-acting actuator, first and second independently operable valves disposed between the inlet port and the first and second control ports, and a main check valve disposed between the inlet port and the first and second independently operable valves.
In another aspect of the invention, a method is provided to control fluid flow to and from first and second double-acting actuators in an independent function mode and a regenerative function mode. The method includes providing a first independent metering valve having a first check control mechanism in fluid communication with the first and second double-acting actuators, providing a second independent metering valve having a main check valve in fluid communication with the first and second double-acting actuator, and operating the first control check control mechanism to allow the first and second actuators to selectively operate in independent and regenerative function modes.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.